Angewandte Chemie International Edition

Cover image for Vol. 52 Issue 16

April 15, 2013

Volume 52, Issue 16

Pages 4275–4491

  1. Cover Pictures

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Author Profile
    6. News
    7. Book Review
    8. Minireview
    9. Review
    10. Communications
    1. You have free access to this content
      Cover Picture: De Novo Design of Nanostructured Iron–Cobalt Fischer–Tropsch Catalysts (Angew. Chem. Int. Ed. 16/2013) (page 4275)

      Dr. V. Roberto Calderone, Dr. N. Raveendran Shiju, Dr. Daniel Curulla-Ferré, Dr. Stéphane Chambrey, Prof. Andrei Khodakov, Amadeus Rose, Johannes Thiessen, Prof. Dr. Andreas Jess and Prof. Dr. Gadi Rothenberg

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201301758

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      A recording industry patent from the 1960s forms the inspiration for designing new core–shell Fischer–Tropsch catalysts. By tweaking the deposition and layer-growth process, G. Rothenberg et al. show in their Communication on page 4397 ff. how uniform spherical particles of iron oxide coated with a 1 nm cobalt shell can be prepared. Pelleted together with nanosized alumina particles, these catalysts are stable up to 673 K, and give good diesel fractions under Fischer–Tropsch conditions.

    2. You have free access to this content
      Inside Cover: Isolation of a Neutral P8 Cluster by [2+2] Cycloaddition of a Diphosphene Facilitated by Carbene Activation of White Phosphorus (Angew. Chem. Int. Ed. 16/2013) (page 4276)

      Dr. Christopher L. Dorsey, Brian M. Squires and Prof. Todd W. Hudnall

      Article first published online: 9 APR 2013 | DOI: 10.1002/anie.201302123

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      Piecing together a carbonyl-decorated carbene and P4 affords the two transient diphosphenes (puzzle pieces in foreground) that rapidly dimerize to give a P8 allotrope (X-ray structure). Whereas nucleophilic carbenes stabilize main-group allotropes, in their Communication on page 4462 ff., T. W. Hudnall and co-workers show how the electrophilicity of carbenes dictates reactivity toward P4. By modulating carbene electrophilicity, two allotropes of phosphorus can be isolated and characterized.

    3. You have free access to this content
      Inside Back Cover: Understanding CO2 Dynamics in Metal–Organic Frameworks with Open Metal Sites (Angew. Chem. Int. Ed. 16/2013) (page 4493)

      Li-Chiang Lin, Dr. Jihan Kim, Dr. Xueqian Kong, Eric Scott, Thomas M. McDonald, Prof. Dr. Jeffrey R. Long, Prof. Dr. Jeffrey A. Reimer and Prof. Dr. Berend Smit

      Article first published online: 8 APR 2013 | DOI: 10.1002/anie.201302125

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      A better understanding of carbon dioxide dynamics in metal–organic frameworks (MOFs) can lead to the optimal design of materials for carbon-capture applications. In their Communication on page 4410 ff., L.-C. Lin et al. utilized molecular simulation techniques to analyze CO2 dynamics inside MOFs with open metal sites. They identified the hopping motion of CO2 between different metal sites as the signature of the experimentally measured patterns in the 13C NMR chemical shift anisotropy.

    4. You have free access to this content
      Back Cover: Detection of the Elusive Highly Charged Zintl Ions Si44− and Sn44− in Liquid Ammonia by NMR Spectroscopy (Angew. Chem. Int. Ed. 16/2013) (page 4494)

      Dr. Maria Neumeier, Franziska Fendt, Dr. Stefanie Gärtner, Carina Koch, Dr. Tobias Gärtner, Prof. Dr. Nikolaus Korber and Prof. Dr. Ruth M. Gschwind

      Article first published online: 8 APR 2013 | DOI: 10.1002/anie.201302288

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      Tetrahedral cages of tin and silicon are well-established in solid compounds of these elements with electropositive metals, but for a long time, doubt remained as to whether the classic Zintl formulation of a complete charge transfer would lead to stable anions if extracted by solvents. In their Communication on page 4483 ff., N. Korber, R. M. Gschwind, and co-workers present the detection by NMR spectroscopy of Sn44− and Si44− dissolved in liquid ammonia.

  2. Graphical Abstract

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    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Author Profile
    6. News
    7. Book Review
    8. Minireview
    9. Review
    10. Communications
    1. Graphical Abstract: Angew. Chem. Int. Ed. 16/2013 (pages 4279–4290)

      Article first published online: 11 APR 2013 | DOI: 10.1002/anie.201390015

  3. News

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Author Profile
    6. News
    7. Book Review
    8. Minireview
    9. Review
    10. Communications
  4. Author Profile

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Author Profile
    6. News
    7. Book Review
    8. Minireview
    9. Review
    10. Communications
    1. Yasushi Morita (page 4298)

      Article first published online: 20 DEC 2012 | DOI: 10.1002/anie.201208429

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      “If I were not a scientist, I would be an archeologist. The most important thing I learned from my parents is patience and modesty. …” This and more about Yasushi Morita can be found on page 4298.

  5. News

    1. Top of page
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    3. Graphical Abstract
    4. News
    5. Author Profile
    6. News
    7. Book Review
    8. Minireview
    9. Review
    10. Communications
  6. Book Review

    1. Top of page
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    7. Book Review
    8. Minireview
    9. Review
    10. Communications
    1. Natural Products in Chemical Biology. Edited by Natanya Civjan. (page 4300)

      Roderich D. Süssmuth

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201301127

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      John Wiley & Sons, Hoboken, 2012. 436 pp., hardcover, € 100.20.—ISBN 978-1118101179

  7. Minireview

    1. Top of page
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    8. Minireview
    9. Review
    10. Communications
    1. Heavier Ketones

      Chemical Tricks To Stabilize Silanones and Their Heavier Homologues with E[DOUBLE BOND]O Bonds (E=Si–Pb): From Elusive Species to Isolable Building Blocks (pages 4302–4311)

      Dr. Yun Xiong, Dr. Shenglai Yao and Prof. Dr. Matthias Driess

      Article first published online: 1 MAR 2013 | DOI: 10.1002/anie.201209766

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      Getting heavy: Recent progress in stable compounds with E[DOUBLE BOND]O bonds (E=Si, Ge, Sn, Pb) is presented. The synthesis of a series of silanone complexes and the first stable “genuine” germanone are the most noteworthy developments in the field of heavier ketone analogues. The structural and spectroscopic data obtained on these new species and their reactivity have greatly enriched the chemical knowledge on heavier ketones.

  8. Review

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    8. Minireview
    9. Review
    10. Communications
    1. Phase-Transfer Catalysis

      Recent Developments in Asymmetric Phase-Transfer Reactions (pages 4312–4348)

      Dr. Seiji Shirakawa and Prof. Dr. Keiji Maruoka

      Article first published online: 28 FEB 2013 | DOI: 10.1002/anie.201206835

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      Work in process: The variations in the synthetic applications of phase-transfer reactions between 2006 and the middle of 2012 have been summarized to show the recent progress made in this field. The reactions have been applied to the synthesis of biologically active natural products and the large-scale preparation of drugs. The conceptually new catalyst design, reaction system, and reaction mode are also described.

  9. Communications

    1. Top of page
    2. Cover Pictures
    3. Graphical Abstract
    4. News
    5. Author Profile
    6. News
    7. Book Review
    8. Minireview
    9. Review
    10. Communications
    1. Epigenetic Markers

      Single-Molecule Detection of 5-Hydroxymethylcytosine in DNA through Chemical Modification and Nanopore Analysis (pages 4350–4355)

      Dr. Wen-Wu Li, Lingzhi Gong and Prof. Hagan Bayley

      Article first published online: 4 APR 2013 | DOI: 10.1002/anie.201300413

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      DNA threading the needle: A new method of single-molecule detection of 5-hydroxymethylcytosine (5hmC) in DNA has been developed. Selective thiol substitution of 5hmC (giving SMC) in a single-step, bisulfite-mediated reaction (see scheme) allows the incorporation of a peptide (yellow sphere) or biotin into DNA. Modified 5hmC bases can be readily distinguished at the single-molecule level using protein nanopore analysis.

    2. Halogen Bonding

      You have full text access to this OnlineOpen article
      A Catenane Assembled through a Single Charge-Assisted Halogen Bond (pages 4356–4360)

      Lydia C. Gilday, Dr. Thomas Lang, Dr. Antonio Caballero, Dr. Paulo J. Costa, Prof. Vítor Félix and Prof. Paul D. Beer

      Article first published online: 11 MAR 2013 | DOI: 10.1002/anie.201300464

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      Getting connected: The formation of pseudorotaxane assemblies between a designed macrocyclic halogen bonding (XB) acceptor (red in scheme) and a series of XB donor threading components was templated by a single halogen bond. The strength of the XB assembly between the pyridine macrocycle and iodopyridinium thread was utilized in the ring-closing metathesis clipping synthesis of a [2]catenane.

    3. Nanostructures

      Ultrathin Nanosheets of MAX Phases with Enhanced Thermal and Mechanical Properties in Polymeric Compositions: Ti3Si0.75Al0.25C2 (pages 4361–4365)

      Xiaodong Zhang, Prof. Jianguang Xu, Hui Wang, Jiajia Zhang, Hanbing Yan, Prof. Bicai Pan, Prof. Jingfang Zhou and Prof. Yi Xie

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201300285

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      TSAC nanosheets: A substitutional solid solution based exfoliation method (see figure) has been developed for the preparation of ultrathin nanosheets of Ti3Si0.75Al0.25C2 (TSAC; Ti green, Si purple, Al yellow, C gray). The as-exfoliated nanosheets show excellent thermal and mechanical properties and can be used as effective fillers in polymer composites, such as with poly(methyl methacrylate).

    4. Bifunctional Materials

      Magnetic Tuning of Upconversion Luminescence in Lanthanide-Doped Bifunctional Nanocrystals (pages 4366–4369)

      Dr. Yunxin Liu, Dr. Dingsheng Wang, Jianxin Shi, Dr. Qing Peng and Prof. Yadong Li

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201209884

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      Nanocrystal clear: Optical-magnetic (OM) bifunctional NaGdF4:Nd3+,Yb3+,Er3+ nanocrystals were successfully synthesized that consist of luminescent Er3+ ions and a coordinating magnetic Gd3+ ion. The luminescence of NaGdF4:Nd3+,Yb3+,Er3+ nanocrystals was tuned by changing the applied magnetic field (see figure) both at room temperature and ultralow temperatures.

    5. Protein Structures

      Probing the Conformational Diversity of Cancer-Associated Mutations in p53 with Ion-Mobility Mass Spectrometry (pages 4370–4374)

      Ewa Jurneczko, Faye Cruickshank, Dr. Massimiliano Porrini, Dr. David J. Clarke, Dr. Iain D. G. Campuzano, Dr. Michael Morris, Dr. Penka V. Nikolova and Dr. Perdita E. Barran

      Article first published online: 14 MAR 2013 | DOI: 10.1002/anie.201210015

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      Conformational flexibility: The DNA-binding domain of tumor suppressor protein p53 (see picture) is characterized by using ion-mobility mass spectrometry. Wild-type p53 and common single-point carcinogenic mutations exhibit diverse conformational states upon transfer into a solvent-free environment of the mass spectrometer. DNA-binding properties of wild-type p53 and an engineered second-site suppressor mutation H115N were also investigated.

    6. Drug Delivery

      NIR-Triggered Anticancer Drug Delivery by Upconverting Nanoparticles with Integrated Azobenzene-Modified Mesoporous Silica (pages 4375–4379)

      Jianan Liu, Prof. Wenbo Bu, Limin Pan and Prof. Jianlin Shi

      Article first published online: 12 MAR 2013 | DOI: 10.1002/anie.201300183

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      Photomediated drug release: Silica-coated upconverting nanoparticles with mesopores modified by azobenzene molecules were synthesized. The azobenzene molecules make possible the release of the anticancer drug doxorubicin from the pore network of the mesoporous silica outer layer by irradiation with near-infrared (NIR) laser light. The release is regulated by the transcis photoisomerization of the azobenzene molecules (see picture).

    7. Solvent Effects

      Microhydration Effects on the Intermediates of the SN2 Reaction of Iodide Anion with Methyl Iodide (pages 4380–4383)

      Keisuke Doi, Eijiro Togano, Dr. Sotiris S. Xantheas, Ryuzo Nakanishi, Prof. Takashi Nagata, Prof. Takayuki Ebata and Dr. Yoshiya Inokuchi

      Article first published online: 30 JAN 2013 | DOI: 10.1002/anie.201207697

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      Water gets in the way: Hydrated I(CH3I) complexes, I(CH3I)(H2O)1–3, are investigated by IR photodissociation spectroscopy to examine the stable structures of the intermediates of the I+CH3I[RIGHTWARDS ARROW]ICH3+I SN2 reaction under hydrated conditions. The structures and the energetics of the complexes suggest that just one or two H2O molecules will effectively inhibit this SN2 reaction.

    8. Drug Delivery

      On-Demand Drug Release System for In Vivo Cancer Treatment through Self-Assembled Magnetic Nanoparticles (pages 4384–4388)

      Dr. Jae-Hyun Lee, Dr. Kuan-Ju Chen, Seung-Hyun Noh, Dr. Mitch André Garcia, Prof. Hao Wang, Prof. Wei-Yu Lin, Heeyeong Jeong, Brian Junoh Kong, Prof. David B. Stout, Prof. Jinwoo Cheon and Prof. Hsian-Rong Tseng

      Article first published online: 20 MAR 2013 | DOI: 10.1002/anie.201207721

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      On-demand drug release: Magnetothermally responsive drug-encapsulated supramolecular nanoparticles for on-demand drug release in vivo have been developed. The remote application of an alternative magnetic field heats the magnetic particles that effectively trigger the release of the drug. An acute drug concentration can be delivered to the tumor in vivo, resulting in an improved therapeutic outcome.

    9. Methanol Steam Reforming

      High CO2 Selectivity in Methanol Steam Reforming through ZnPd/ZnO Teamwork (pages 4389–4392)

      Matthias Friedrich, Dr. Simon Penner, Dr. Marc Heggen and Dr. Marc Armbrüster

      Article first published online: 11 MAR 2013 | DOI: 10.1002/anie.201209587

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      Together we are strong: Immediately after high-temperature reduction, ZnPd/ZnO catalysts are not notably CO2 selective in the methanol steam reforming process. Under methanol steam reforming conditions, high CO2 selectivity can only be achieved by the rather slow formation of ZnO patches on the surface of intermetallic ZnPd nanoparticles to create a highly synergistic interface.

    10. Supramolecular Chemistry

      Enantioselective Cyclization of Photochromic Dithienylethenes Bound to DNA (pages 4393–4396)

      Dr. Tamara C. S. Pace, Vilhelm Müller, Dr. Shiming Li, Prof. Dr. Per Lincoln and Prof. Dr. Joakim Andréasson

      Article first published online: 7 MAR 2013 | DOI: 10.1002/anie.201209773

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      Guiding light: Enantioselectivity is obtained for the photocyclization of a photochromic dithienylethene when isomerization is carried out in the presence of DNA (see scheme).

    11. Core–Shell Catalysts

      De Novo Design of Nanostructured Iron–Cobalt Fischer–Tropsch Catalysts (pages 4397–4401)

      Dr. V. Roberto Calderone, Dr. N. Raveendran Shiju, Dr. Daniel Curulla-Ferré, Dr. Stéphane Chambrey, Prof. Andrei Khodakov, Amadeus Rose, Johannes Thiessen, Prof. Dr. Andreas Jess and Prof. Dr. Gadi Rothenberg

      Article first published online: 28 FEB 2013 | DOI: 10.1002/anie.201209799

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      Audio cassettes hold the key to enhancing Fischer–Tropsch catalysis. Catalysts based on ultra-thin cobalt shells surrounding cheap iron oxide cores (see picture) are developed, an approach previously optimized for preparing magnetic tape for audio cassettes. These particles are easily made on a large scale, and are excellent Fischer–Tropsch catalysts, giving good diesel fractions.

    12. Molecular Recognition

      Chirped-Pulse and Cavity-Based Fourier Transform Microwave Spectra of the Methyl Lactate⋅⋅⋅Ammonia Adduct (pages 4402–4405)

      Javix Thomas, Dr. Oleksandr Sukhorukov, Prof. Dr. Wolfgang Jäger and Prof. Dr. Yunjie Xu

      Article first published online: 14 MAR 2013 | DOI: 10.1002/anie.201300707

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      Internal rotations: Using a broadband chirped-pulse and a cavity-based microwave spectrometer, the delicate balance between intra- and intermolecular hydrogen-bonding interactions in the methyl lactate⋅⋅⋅NH3 adduct was investigated (see picture). The adduct is a prototype lock-and-key system consisting of a lock with two “spinning” tops and a key which is also a spinning top itself.

    13. Hydrogen Storage

      An Efficient CoAuPd/C Catalyst for Hydrogen Generation from Formic Acid at Room Temperature (pages 4406–4409)

      Zhi-Li Wang, Prof. Jun-Min Yan, Yun Ping, Hong-Li Wang, Prof. Wei-Tao Zheng and Prof. Qing Jiang

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201301009

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      Less noble: The Co0.30Au0.35Pd0.35 nanoalloy supported on carbon is reported as a stable, low-cost, and highly efficient catalyst for the CO-free hydrogen generation from formic acid dehydrogenation at room temperature (see picture). The method may strongly encourage the practical application of formic acid as a hydrogen storage material for fuel cells.

    14. CO2 Dynamics

      Understanding CO2 Dynamics in Metal–Organic Frameworks with Open Metal Sites (pages 4410–4413)

      Li-Chiang Lin, Dr. Jihan Kim, Dr. Xueqian Kong, Eric Scott, Thomas M. McDonald, Prof. Dr. Jeffrey R. Long, Prof. Dr. Jeffrey A. Reimer and Prof. Dr. Berend Smit

      Article first published online: 28 MAR 2013 | DOI: 10.1002/anie.201300446

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      Hopping along: Metal–organic frameworks such as Mg-MOF-74 possess open metal sites that interact strongly with CO2. Molecular simulations reveal detailed CO2 dynamics (hops between metal sites and localized fluctuations), which can be used to accurately explain the experimentally measured 13C NMR chemical shift anisotropy pattern.

    15. Asymmetric Catalysis

      Silver-Catalyzed Allenylation and Enantioselective Propargylation Reactions of Ketones (pages 4414–4417)

      Benjamin L. Kohn, Naoko Ichiishi and Prof. Elizabeth R. Jarvo

      Article first published online: 12 MAR 2013 | DOI: 10.1002/anie.201206971

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      More than a silver lining: Certain silver complexes are capable of selective catalysis of either allenylation or asymmetric propargylation reactions of ketones. Ligand-free conditions lead to allenyl alcohols as the major product, whereas ligation with Walphos-8 gives enantioenriched homopropargyl alcohols. This method can be applied to reactions of prochiral diarylketones to provide optically enriched tertiary diaryl alcohols.

    16. C[BOND]H Alkylation

      Yttrium-Catalyzed Addition of Benzylic C[BOND]H Bonds of Alkyl Pyridines to Olefins (pages 4418–4421)

      Dr. Bing-Tao Guan, Dr. Baoli Wang, Dr. Masayoshi Nishiura and Prof. Dr. Zhaomin Hou

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201208867

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      Cationic half-sandwich yttrium alkyl complexes catalyze the ortho-selective benzylic C[BOND]H addition of dialkyl pyridines to various olefins, such as ethylene, 1-hexene, styrenes, and 1,3-conjugated dienes, to afford new alkylated and allylated pyridine derivatives (see scheme; Cp=C5Me5). A cationic half-sandwich yttrium picolyl species, such as [CpY(2-CH2-6-CH3C5H3N)]+, has been confirmed to be a key active species in this transformation.

    17. Carbon Materials

      Aligning the Band Gap of Graphene Nanoribbons by Monomer Doping (pages 4422–4425)

      Christopher Bronner, Stephan Stremlau, Dr. Marie Gille, Felix Brauße, Anton Haase, Prof. Dr. Stefan Hecht and Prof. Dr. Petra Tegeder

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201209735

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      A matter of doping: Graphene nanoribbons (GNRs) were generated through an on-surface bottom-up synthesis and selectively doped at their edges by introducing nitrogen atoms in the precursor monomers. While the size of the band gap of 2.8 eV remains almost unchanged upon N substitution, a linear shift of the band structure is observed and corresponds to n-type doping (see picture; CB=conduction band and VB=valence band).

    18. Small-Ring Systems

      Synthesis of a Donor-Stabilized Silacyclopropan-1-one (pages 4426–4430)

      Dr. Ricardo Rodriguez, Dr. Thibault Troadec, Dr. David Gau, Dr. Nathalie Saffon-Merceron, Dr. Daisuke Hashizume, Dr. Karinne Miqueu, Dr. Jean-Marc Sotiropoulos, Dr. Antoine Baceiredo and Dr. Tsuyoshi Kato

      Article first published online: 8 APR 2013 | DOI: 10.1002/anie.201210010

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      As intriguing as the Bermuda Triangle: The synthesis and characterization of an isolable silacyclopropan-1-one (see structure; red O, blue N, green Si, yellow P) was made possible by stabilization through intramolecular coordination by a Lewis base. However, this silacyclopropan-1-one, which contains a significantly elongated endocyclic C[BOND]C σ bond, remains highly reactive and underwent an unprecedented silanone–silenol rearrangement under mild conditions.

    19. Borylation Reactions

      Palladium-Catalyzed ortho-Selective C[BOND]H Borylation of 2-Phenylpyridine and Its Derivatives at Room Temperature (pages 4431–4434)

      Prof. Dr. Yoichiro Kuninobu, Takashi Iwanaga, Tetsuya Omura and Prof. Dr. Kazuhiko Takai

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201210328

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      Boron delivery: C[BOND]H borylation at the ortho-position of aromatic compounds is promoted by the treatment of 2-phenylpyridine, or its derivatives, with 9-borabicyclo[3.3.1]nonane in the presence of a palladium catalyst. This reaction proceeds at room temperature and can be conducted without the palladium catalyst at higher temperatures. In both cases, the regioselectivity is controlled by Lewis acid–base interaction between the boron and nitrogen atoms.

    20. Glycopolymers

      Sequence-Controlled Multi-Block Glycopolymers to Inhibit DC-SIGN-gp120 Binding (pages 4435–4439)

      Qiang Zhang, Jennifer Collins, Athina Anastasaki, Dr. Russell Wallis, Dr. Daniel A. Mitchell, Dr. C. Remzi Becer and Prof. David M. Haddleton

      Article first published online: 11 MAR 2013 | DOI: 10.1002/anie.201300068

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      Chain of command: Multi-block glycopolymers made of mannose (M, see figure), glucose, and di(ethylene glycol) ethyl ether (D) monomers were synthesized using a technique to control the polymer sequence. These highly monodisperse glycopolymers were then tested for binding and inhibition of DC-SIGN, a protein important for HIV infection.

    21. C[BOND]H Activation

      Regio- and Chemoselective C[BOND]H Chlorination/Bromination of Electron-Deficient Arenes by Weak Coordination and Study of Relative Directing-Group Abilities (pages 4440–4444)

      Xiuyun Sun, Gang Shan, Yonghui Sun and Prof. Dr. Yu Rao

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201300176

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      It's all relative: A practical and efficient PdII-catalyzed regio- and chemoselective chlorination/bromination has been developed for the facile synthesis of a broad range of aromatic chlorides. The reaction demonstrates excellent reactivity, good functional-group tolerance, and high yields. A preliminary study was conducted to evaluate relative directing-group abilities of various functionalities.

    22. Alkynyl Diphosphane Complexes

      Redox-Induced Reversible P[BOND]P Bond Formation to Generate an Organometallic σ4λ4-1,2-Biphosphane Dication (pages 4445–4448)

      Ayham Tohmé, Dr. Guillaume Grelaud, Dr. Gilles Argouarch, Dr. Thierry Roisnel, Dr. Stéphanie Labouille, Dr. Duncan Carmichael and Dr. Frédéric Paul

      Article first published online: 14 MAR 2013 | DOI: 10.1002/anie.201208682

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      Twice the fun: Dimeric FeII diphosphonium bis(alkynyl) complexes are formed by oxidation of the corresponding FeII alkynyl phosphine complexes. The structure of these organometallic diphosphonium salts and their monomeric precursors were established by X-ray crystallography. The P[BOND]P bond can be cleaved by two-electron reduction to regenerate the monomers.

    23. Heterometallic Complexes

      Multiple Metal–Metal Bonds in Iron–Chromium Complexes (pages 4449–4452)

      P. Alex Rudd, Shengsi Liu, Dr. Nora Planas, Dr. Eckhard Bill, Prof. Dr. Laura Gagliardi and Prof. Dr. Connie C. Lu

      Article first published online: 11 MAR 2013 | DOI: 10.1002/anie.201208686

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      Mix and match: The first structural examples of M[BOND]M multiple bonds between different first-row transition metals are elucidated using X-ray crystallography (see picture; Fe pink, Cr green, P yellow, N blue), spectroscopic methods, and calculations. The Fe[BOND]Cr bonds are ultrashort (<2 Å) with highly delocalized σ and π bonds and unusually large quadrupole splittings in Mössbauer spectroscopy.

    24. C-H Functionalization

      Direct Functionalization of Tetrahydrofuran and 1,4-Dioxane: Nickel-Catalyzed Oxidative C(sp3)[BOND]H Arylation (pages 4453–4456)

      Dong Liu, Dr. Chao Liu, Heng Li and Prof. Aiwen Lei

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201300459

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      CHoose nickel: The nickel-catalyzed oxidative arylation of C(sp3)[BOND]H bonds has been achieved. Several substituted arylboronic acids and various C(sp3)[BOND]H bonds were found to be suitable substrates for this novel transformation, which is likely to proceed through a radical pathway. This method allows the introduction of simple ether derivatives to construct α-arylated ethers. FG=functional group.

    25. Synthetic Methods

      Copper-Mediated C[BOND]H/C[BOND]H Biaryl Coupling of Benzoic Acid Derivatives and 1,3-Azoles (pages 4457–4461)

      Mayuko Nishino, Dr. Koji Hirano, Prof. Dr. Tetsuya Satoh and Prof. Dr. Masahiro Miura

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201300587

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      Hot couple: A precious-metal-free copper-mediated intermolecular direct biaryl coupling of benzoic acid derivatives and 1,3-azoles has been developed. The key to success is the installation of an amide-based bidentate coordinating group, which is easily removed and transformed into the parent ester groups after the coupling reaction. Kinetic studies indicate that the rate-limiting step is the aromatic C[BOND]H bond cleavage of benzoic acid derivatives.

    26. Phosphorus Clusters

      Isolation of a Neutral P8 Cluster by [2+2] Cycloaddition of a Diphosphene Facilitated by Carbene Activation of White Phosphorus (pages 4462–4465)

      Dr. Christopher L. Dorsey, Brian M. Squires and Prof. Todd W. Hudnall

      Article first published online: 8 APR 2013 | DOI: 10.1002/anie.201301137

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      P-cing it together: Carbonyl-decorated carbenes readily activate white phosphorus to afford carbene-stabilized P4 and P8 clusters. Mechanistic evidence suggests the P8 cluster (see structure from X-ray diffraction: C gray, P orange, N blue, O red) forms by a [2+2] cycloaddition of a transient diphosphene species.

    27. Asymmetric Catalysis

      Enantioselective Synthesis of 2,2-Disubstituted Tetrahydrofurans: Palladium-Catalyzed [3+2] Cycloadditions of Trimethylenemethane with Ketones (pages 4466–4469)

      Prof. Barry M. Trost and Dr. Dustin A. Bringley

      Article first published online: 12 MAR 2013 | DOI: 10.1002/anie.201300616

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      O rings: An approach to the title compounds has been developed utilizing a cycloaddition of trimethylenemethane with aryl ketones. The products are formed in up to a 96 % yield with 95 % ee. The reaction is catalyzed by palladium in the presence of L1, which possesses a stereogenic phosphorus atom, and only a single epimer at the phosphorus atom yields the active catalyst. Cp=cyclopentadiene, TMS=trimethylsilyl.

    28. Natural Products Synthesis

      Total Synthesis of Cyanolide A in the Absence of Protecting Groups, Chiral Auxiliaries, or Premetalated Carbon Nucleophiles (pages 4470–4473)

      Andrew R. Waldeck and Prof. Michael J. Krische

      Article first published online: 11 MAR 2013 | DOI: 10.1002/anie.201300843

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      No protection, no problem: The C2-symmetric macrodiolide cyanolide A is prepared in six steps from neopentyl glycol and allyl acetate by iridium-catalyzed double asymmetric allylation and a tandem cross-metathesis/oxa-Michael cyclization to form the substituted pyran. The synthesis is accomplished in the absence of any protecting groups, chiral auxiliaries, or premetalated carbon nucleophiles in fewer than half the steps of any prior approach.

    29. Acetals

      The Catalytic Asymmetric Acetalization (pages 4474–4477)

      Ji Hye Kim, Ilija Čorić, Dr. Sreekumar Vellalath and Prof. Dr. Benjamin List

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201300120

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      In straitened circumstances: In an asymmetric version of the acid-catalyzed acetalization of aldehydes, a novel member of the chiral confined Brønsted acid family significantly outperformed previously established catalysts, providing cyclic acetals with excellent enantioselectivity (see scheme; Ar=2-iPr-5-MeC6H3).

    30. Hexasilabenzene

      An Experimental Charge Density Study of Two Isomers of Hexasilabenzene (pages 4478–4482)

      Daniel Kratzert, Dr. Dirk Leusser, Dr. Julian J. Holstein, Dr. Birger Dittrich, Kai Abersfelder, Prof. Dr. David Scheschkewitz and Prof. Dr. Dietmar Stalke

      Article first published online: 14 MAR 2013 | DOI: 10.1002/anie.201209906

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      The aromaticity of the ring and cage isomer of a hexasilabenzene derivative was investigated by experimentally determined charge-density distribution. Topological analysis and valence-shell charge concentrations reflect the degree of delocalization in the various bonds. A transannular Si0–SiI bond was found in the ring conformer, while an interstitial Si0–Si0 bond along the hub in the silapropellane moiety of the cage conformer was not detected.

    31. Main-Group Chemistry

      Detection of the Elusive Highly Charged Zintl Ions Si44− and Sn44− in Liquid Ammonia by NMR Spectroscopy (pages 4483–4486)

      Dr. Maria Neumeier, Franziska Fendt, Dr. Stefanie Gärtner, Carina Koch, Dr. Tobias Gärtner, Prof. Dr. Nikolaus Korber and Prof. Dr. Ruth M. Gschwind

      Article first published online: 20 MAR 2013 | DOI: 10.1002/anie.201209578

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      It's detected! The existence of the prototypical Zintl ions Tt44− (Tt=Group 14 element), which are isoelectronic to the P4 molecule, used to be confined to the solid state. Recently, circumstantial evidence for a solution chemistry in liquid ammonia emerged. Direct spectroscopic observation of the dissolved anions has now been achieved. In the case of Si44−, this is the first solution detection of any homoatomic silicide.

    32. Protein–Protein Interactions

      Oral Disinfectants Inhibit Protein–Protein Interactions Mediated by the Anti-Apoptotic Protein Bcl-xL and Induce Apoptosis in Human Oral Tumor Cells (pages 4487–4491)

      Dr. Martin Gräber, Dipl.-Chem. Michael Hell, M. Sc. Corinna Gröst, Dr. Anders Friberg, Bianca Sperl, Prof. Dr. Michael Sattler and Prof. Dr. Thorsten Berg

      Article first published online: 19 MAR 2013 | DOI: 10.1002/anie.201208889

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      Chlorhexidine and alexidine have long been used as oral disinfectants by humans. Both compounds inhibit protein–protein interactions mediated by the anti-apoptotic protein Bcl-xL at physiologically relevant concentrations and induce apoptosis in a series of tumor cell lines derived from the tongue and pharynx (see picture). Inhibition of protein–protein interactions is a potential mode of action of drugs in current human use.

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